Question

A pull of 20N, inclined at 25⁰ to the horizontal plane, is required just to move a body
placed on a rough horizontal plane. But the push required to move the body is 25N. If the
push inclined at 25⁰ to the horizontal, find the weight of the body and coefficient of friction

Answer 1

Answer:

Coefficient of friction between block and ground is 0.24 and weight of the object is 84.5 N

Explanation:

As we know that the pull required to move the object is 20 N at 25 degree

so we have

$F_n + 20 sin 25 = mg$

$F_n = mg - 20 sin25$

now we have

$F_x = F_f$

$20 cos25 = \mu(mg - 20 sin25)$

Now we know that push of 25 N is required the same body at 25 degree

so we have

$F_n = mg + 25 sin25$

also in horizontal direction we have

$F_x = F_f$

now we have

$25 cos25 = \mu(mg + 25 sin25)$

now divide both equations we have

$\frac{20}{25} = \frac{mg - 20 sin25}{mg + 25 sin25}$

$4mg + 100 sin25 = 5mg - 100 sin25$

$mg = 200 sin25$

$W = mg = 84.5 N$

now we have

$\mu = 0.24$

#Learn

Topic : Newtons law and friction

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Answer 2

Answer:

Explanation:

Angle of repose is simply the angle of inclination for which friction is max. i.e. u=tan(theta). If angle of inclination is less than the max. angle then friction will b more as tan theta has nw bcm small due to smaller angle, if angle of inclination is more than the theta for max friction then the block will slide down as friction wont b enogh to stop that block. In ur qstion its said that block has to b pushed down so angle of inclination is less than the angle or thetafor max. friction do option C is correct. Its kind of messy wht i wrote but read it twice or more n also frm ur physics book or notes u ll get it. Its very simple.Hope it helps!!